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5), ground water elevation is approximately 15 to 20 feet above mean sea level; the ground-water flow beneath the Site is to the north at a rate of approximately 8 to 12 feet per mile. Given that the ground elevation of the Site is approximately 55 feet above mean sea level, the depth to water below the Site is estimated to be approximately 35 to 40 feet. Potential Ground Water Contamination Issues The Soil Suitability Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground water contamination, including leaking underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground water contamination sources with the potential to impact the Site. Two common ground-water contaminants in San Joaquin County are nitrate and dibromochloropropane (DBCP). Live Oak reviewed the San Joaquin County Environmental Health Department's maps of Nitrate — Land Use Data and DBCP— Land Use Data dated February 20, 2019. According to the nitrate map (Plate 6), four wells within a one-mile radius of the subject Site have been tested for nitrate; it was detected in three of the wells at concentrations between 5.1 and 10.0 mg/L-N, and in the final well at a concentration between 0.1 and 5.0 mg/L-N. According to the DBCP map (Plate 7), two wells within a one-mile radius of the Site have been tested for DBCP; no DBCP was detected in either of the wells. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 µg/L. The surrounding area consists of orchards and occasional rural residences. The Site is located approximately 1.2 mile northeast of the Tracy Defense Depot, a Superfund site which has contaminated ground water in the area with chemicals including trichloroethene, tetrachloroethene, and dieldrin (GeoTracker, 2020). On-Site Wells A domestic well is located on the Site. Two well permits were identified for the Site from among the files of the San Joaquin County Environmental Health Department: • December 2018 permit for new domestic well. According to the permit, the well was 300 feet deep with a grout seal at 100 feet. The attached soil log indicates alternating layers of clay and sand. • May 2019 permit for new pump at domestic well. These permits have been included in Appendix 4 of this report. LOGE 2106 Page 3